1. Field of the Invention
This invention relates to a magnetostatic wave device and, more particularly, to the same having both an input and output antennas.
2. Description of the Prior Art
FIG. 7 is a perspective view showing one example of the conventional magnetostatic wave devices which constitutes the background of the present invention. The magnetostatic wave device 1 comprises a thin film 2 of YIG (yttrium iron garnet), which the YIG thin film 2 is formed on one principal surface of a GGG (gadolinium gallium garnet) substrate 3. Further, on the YIG thin film 2, one input antenna 4 and one output antenna 5 are provided having a spacing between them. One terminal of the input antenna 4 is grounded and the other is connected to an input terminal (not shown). Further, one terminal of the output antenna 5 is grounded and the other is connected to an output terminal (not shown).
A magnetic field is applied to the magnetostatic wave device 1. Then, in the magnetostatic wave device 1, an input signal entered into the input antenna 4 is excited as a magnetostatic wave, which is propagated on the YIG thin film 2 and received by the output antenna 5.
However, in the magnetostatic wave device 1, the magnetostatic wave is propagated from the input antenna in two directions, that is, the direction shown with arrow B and its opposite one, and only the magnetostatic wave propagated in one direction (direction shown with arrow B) can be received. Therefore, in this magnetostatic wave device 1, a half of total energy is lost in principle.